1. Field of the Invention
The invention relates to a bearing arrangement in the form of a bearing, large rolling bearing, or rotary joint, with devices for integrated cooling and/or heating, and to a method for the integrated heating or cooling of a bearing, large rolling bearing, slew drive, or rotary joint.
2. Description of the Prior Art
Currently available and currently used large rolling bearings, bearings, and universal rotary joints for machine and plant engineering, and which can be used in slew drives to prevent excessive cooling of bearing components—especially the stressed components in and around the raceways of the rotary joint(s)—are cooled with a liquid or an oil. Technical solutions also exist in which the bearing components, especially the stressed components, are heated by means of a liquid or an oil, or by an electrical heating system.
Such large rolling bearings, bearings, and universal rotary joints, for machine and plant engineering, are also often used in applications of this kind that involve sharp temperature fluctuations and/or extreme operating conditions. Specifically, such parts are commonly used in wind power plants, cranes, ship cranes, tunnel construction, and all other conceivable areas of application. Regardless of circumstances, large rolling bearings, bearings and universal rotary joints for machine and plant engineering, are likely to be exposed to extreme temperature and environmental conditions, and thus also extreme heat or cold.
DE 102005058141 A1 and the related WO 2007/065412 A1 relate to a rolling bearing having at least one heated rolling-bearing ring, such that an electric heating element is mounted in thermally well-conducting contact on a surface portion of the heated rolling-bearing ring; the amount of heat that can be generated by the heating element is provided such that the heated rolling-bearing ring undergoes thermal expansion when heated. The expansion makes it possible to install the rolling bearing on a frame element so that a shrink fit is created as it subsequently cools.
DE 102008052287 A1 relates to a bearing arrangement comprising
a bearing through which a medium (particularly water) flows and a filter device, which is disposed upstream from the bearing to remove particles from the medium, and a shaft received in the bearing, such that a feed device for the medium is disposed downstream from the bearing and controls the flow of the medium through the bearing.
Other examples of the prior art are the documents DE 2021156 B2, WO 99/35414, DE 4234303 A1 and DE 102004015176 A1, which also describe cooling systems for bearings.
The term “passive or indirect cooling” generally applies when indirect cooling is present, as in the case, for example, of the heat pipe principle, or the convection heating principle. A heat pipe generally functions as a heat transfer device that uses the heat of evaporation of a substance to achieve a high heat flux density, that is, large quantities of heat can be transported through a small cross-sectional area.
The waste heat present in a given part is emitted to the ambient air by the principle of thermal convection, for example via cooling fins, radiators, etc.
To summarize, the technical solutions of the current state of the art, as represented by the above-cited documents, often have the major disadvantage of having been developed either in the context of heating, or in the context of cooling, of components of the bearing arrangement.
Until now, grease-lubricated rotary joints, in particular, have not lent themselves well to direct, active cooling or direct, active heating. Usually, the only solution open to the skilled person is indirect cooling, which is inadequate. At very low temperatures (about −40° C. and below), grease in the bearing is stiff and hinders the operation of the bearing, or the start-up of the installation. At very high temperatures, on the other hand, the oil in the grease becomes low-viscosity, which has a negative effect on the lubricant. Both too-low and too-high temperatures prematurely reduce the quality of the lubricant, so it has to be replaced sooner than normal.